I use the 20mm Vittoria on a narrow hed jet 60 and I really like the wheel and it feels very fast. On my hed jet 90 C2 I use a s works mondo open tubular 23mm which feels a bit better but both wheels feel very fast. I'm running michelin latex tubes in both wheels. My vote would be for the 20mm vittoria!

I've used both. The Evos feel much smoother and faster, but I got a flat in one race. I don't really want to blame the tyre though... I didn't have my track pump with me on race day, so I inflated them with a small portable pump, and I think I didn't get them to normal pressure (I race at close to 120 to minimize chances of flatting). I got a flat in the first 3 miles, replaced the tube, pumped it hard with my CO2, and was fine for the next 109 miles.

They feel great so I will race on them again for sure, just at much higher pressure. The GP4000s are nice, but not as buttery smooth as the evos.

vittoria oc 23mm. the 20mm version has less than optimal rolling resistance that is not offset by its narrowness.

Really? I would have thought that the aforementioned advice was right on: "Totally different tires. Speedwise, the Evos kill the GP4000. Treadwise and flatwise, the GPs win. Train on the GPs. Race on the Evos. "

So, even with a narrow (or- uh, regular sized) wheel, the reduced rolling resistance of a 23mm tire outweighs the aero benefit of a narrow tire on a narrow rim?

I can understand using the 23mm tire on a C2 or Firecrest- but on an S80?

They are fast no doubt, but I need something that i can train on also, roads I ride on have a lot of small stones and debris from cars. And I don't want my front blowing out while I am descending a mountain at 60km/h. Would I as an age grouper notice the difference between by speed on a supersonic or Open Corsa with the same latex tube inside of it?

This is how they are described by conti:

This tyre is intended for race use only in solo events, and is not recommended for road races or training rides due to its short tread life. There is no extra puncture protection with the Grand Prix Supersonic due to the lightweight construction. Riders should weigh up the compromises that they are willing to take before selecting this tyre.

Get a cheap training wheelset with durable training tyres. Keep the S80 wheelset, with Conti Black Chili supersonics, along with the aero lid, for race day. There's one very fast guy on here - nick in the seychelles - who has a full wheelset AND drivetrain exclusively for raceday. Makes a lot of sense. Best of luck whatever you decide ------------------------------- ´Get the most aero and light bike you can get. With the aero advantage you can be saving minutes and with the weight advantage you can be saving seconds. In a race against the clock both matter.´

Totally different tires. Speedwise, the Evos kill the GP4000. Treadwise and flatwise, the GPs win. Train on the GPs. Race on the Evos.

Agreed. The GP are great tires but I find the EVO to be a faster, smoother ride, just not as durable as the GP. But I would suggest sticking with 23mm. The slight aero disadvantage is made up for with a smoother ride and less rolling resistance. Rodney TrainingPeaks | Altra Running | CEP | ICEdot http://www.goinglong.ca

SeasonsChange has made similar comments in other threads. He's said that Bontrager has produced these results, but I haven't been able to find them (and I don't know if he's willing to share this).

As I understand it, the main argument for poor crr on the 20mm version is that the tread width extends too far on to the sidewall (they use the same tread layer on both the 20 and 23mm), thereby compromising the pliability of the sidewall.

I'm likely going to try out the Conti SS 20mm this year (for races only) and see how that holds up.

1x (one-by) is the popular designation for single chainring, no front derailleur. It's at least a moderate hit for SRAM in both MTB (XX1) and cross (CX1). tri (TX1?) seems poised to be next. Would you give this serious consideration for your next tri bike?